DESCRIPTION: Damage to the human brain and spinal cord is generally regarded as irreversible. However, this view of brain organization has been challenged, and up to 1/3 of the primary somatosensory cortex could reorganize in respond to injury to the CNS. At present, the underlying mechanism(s) of such large scale reorganization are not well understood. Five specific aims are proposed. One of the specific aims addresses potential mechanisms by which reorganization might take place. Another question which will be addressed is whether such changes are functionally, or perceptually, significant to the animal in which the changes take place. By understanding the limits, perceptual correlates and neural mechanisms associated with injury induced cortical reorganization, the applicant hope to provide insight as to how to harness this immense capacity of the adult brain to respond to injury so as to provide help to the hundreds and thousands of the people in the US that suffer sensory disorders and neurological impairments due to head or nerve injury each year.